So many people a cup of tea or coffee as soon as they get up, and then on the way to work, they stop at Starbucks or Dunkin’ Donuts and get another. But is this the best time to get one’s caffeine fix?

According to Rachel Gillett’s reading of the science literature, it’s not. That’s because

If we consume coffee, or any caffeine for that matter, during times of peak cortisol production, scientists say that the effect of the caffeine will not only be greatly diminished during that time, but our bodies will also build up a tolerance to the effects of caffeine. That means less buzz for you even when you’re drinking coffee at the right time.

Peak cortisol production occurs after waking up until around 9:30 am and around noon and 5:30 pm, which means we should drink coffee 9:30-11:30 am and 1:30-5:30 pm—although I wouldn’t drink any caffeine after 2:00-2:30 pm as it interferes with my sleep at night.